APE1/Ref-1 regulates STAT3 transcriptional activity and APE1/Ref-1-STAT3 dual-targeting effectively inhibits pancreatic cancer cell survival

• Published in: PloS one 2012-10, Vol.7 (10), p.e47462
• Main Authors: Cardoso, Angelo A, Jiang, Yanlin, Luo, Meihua, Reed, April M, Shahda, Safi, He, Ying, Maitra, Anirban, Kelley, Mark R, Fishel, Melissa L
• Format: Article
• Language: English
• Subjects: Adenocarcinoma; Adenocarcinoma - drug therapy; Adenocarcinoma - genetics; Adenocarcinoma - metabolism; Adenocarcinoma - pathology; Aminosalicylic Acids - pharmacology; Angiogenesis; Apoptosis; Apoptosis - drug effects; Benzenesulfonates - pharmacology; Benzoquinones - pharmacology; Binding; Biological activity; Biology; Bone cancer; Brain cancer; Cancer; Cancer therapies; Caspase; Caspase 3 - genetics; Caspase 3 - metabolism; Caspase-3; Cell Line, Tumor; Cell migration; Cell proliferation; Cell Proliferation - drug effects; Cell survival; Cyclic S-Oxides - pharmacology; Deoxyribonucleic acid; DNA; DNA binding; DNA repair; DNA-(Apurinic or Apyrimidinic Site) Lyase - antagonists & inhibitors; DNA-(Apurinic or Apyrimidinic Site) Lyase - genetics; DNA-(Apurinic or Apyrimidinic Site) Lyase - metabolism; Drug dosages; Drug resistance; Endonuclease; Enzymes; Gene Expression Regulation, Neoplastic - drug effects; Gene Knockdown Techniques; Genetic aspects; Growth factors; Hematology; Humans; Medicine; Molecular Targeted Therapy; Oncology; Oxidation-Reduction; Pancreatic cancer; Pancreatic Neoplasms - drug therapy; Pancreatic Neoplasms - genetics; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; Pediatrics; Pharmacology; Propionates - pharmacology; Proteins; Redox properties; RNA, Small Interfering - genetics; Rodents; Signal processing; Signal transduction; Signal Transduction - drug effects; Signaling; Stat3 protein; STAT3 Transcription Factor - antagonists & inhibitors; STAT3 Transcription Factor - genetics; STAT3 Transcription Factor - metabolism; Survival; Synergism; Toxicology; Transcription (Genetics); Transcription factors; Transcription, Genetic - drug effects; Viability
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0047462

Pancreatic cancer is a largely incurable disease, and increasing evidence supports strategies targeting multiple molecular mediators of critical functions of pancreatic ductal adenocarcinoma cells. Intracellular redox state modulates the activity of various signal transduction pathways and biological processes, including cell survival, drug resistance and responsiveness to microenvironmental factors. Recently, it has been shown that the transcription factor STAT3 is under redox control, but the mechanisms involved in its regulation are unknown. Here, we demonstrate for the first time that STAT3 DNA binding and transcriptional activity is directly regulated by the redox function of the APE1/Ref-1 endonuclease, using overexpression and redox-specific mutational strategies, and gene knockdown. Also, pharmacological blockade of APE1/Ref-1 by the redox-selective inhibitor E3330 abrogates STAT3 DNA binding. Since APE1/Ref-1 also exerts redox control on other cancer-associated transcription factors, we assessed the impact of dual-targeting of STAT3 signaling and APE1/Ref-1 redox on pancreatic cancer cell functions. We observed that disruption of APE1/Ref-1 redox activity synergizes with STAT3 blockade to potently inhibit the proliferation and viability of human PDAC cells. Mechanistically, we show that STAT3-APE1/Ref-1 dual targeting promotes marked tumor cell apoptosis, with engagement of caspase-3 signaling, which are significantly increased in comparison to the effects triggered by single target blockade. Also, we show that STAT3-APE1/Ref-1 dual blockade results in significant inhibition of tumor cell migration. Overall, this work demonstrates that the transcriptional activity of STAT3 is directly regulated by the redox function of APE1/Ref-1, and that concurrent blockade of STAT3 and APE1/Ref-1 redox synergize effectively inhibit critical PDAC cell functions.